function R = getsigma(mdl)
%GETREPR Gets the internal representation of sigma
%
% [ Syntax ]
%   - R = getsigma(mdl)
%
% [ Remarks ]
%   - The internal representation of the sigma for Gaussian model with
%     diagonal form covariance is a d x 1 vector of the diagonal entries
%     in the covariance matrix.
%
% [ History ]
%   - Created by Dahua Lin, on Dec 24, 2007
%

R = mdl.sigma;